SIR: As a student of Herbert Spencer's Philosophy, I have waited impatiently the advent of his "Principles of Sociology," and particularly so of late, as I am greatly interested in the work of an American writer on a kindred subject. I refer to Mr. Lewis H. Morgan's "Ancient Society," lately published by Henry Holt & Co. It is to a comparison of the views of these writers on the origin of the monogamian family that I wish to invite your attention.

In Mr. Morgan's studies of consanguinity and affinity he found certain systems prevailing which could only be explained by the existence of certain forms of marriage, and of the family which produced them. These forms he has named the "Consanguine," the "Punaluan," and the "Monogamian." As before stated, it is the origin of the latter form only that I propose to discuss at present. According to Mr. Morgan, the monogamian family is comparatively modern, and came into existence with the growth of the idea of property. He says (page 477): "The growth of property and the desire for its transmission to children was, in reality, the moving power which brought in monogamy to insure legitimate heirs, and to limit their number to the actual progeny of the married pair." He maintains that exclusive cohabitation, in the sense that we understand it, was not practised until mankind had created property in masses, which they desired should pass into the hands of their offspring, and that the marriage of single pairs previous to this did not constitute monogamy, but formed what he terms the "Syndyasmian or Pairing Family," which differed from monogamy in several essential particulars, chief of which was the fact that "the marriage relation continued during the pleasure of the parties, and no longer," and, so far as the male was concerned, "the absence of an exclusive cohabitation." In reading Mr. Spencer's article on the "Evolution of the Family," it occurred to me that Mr. Morgan's theory answered his question, "Are different forms of domestic arrangement associated with the militant system of organization and the industrial system of organization?" even better than his own. Mr. Spencer remarks that, "on examining the facts more closely, we discern general connections between the militant type and polygyny, and between the industrial type and monogamy." He then calls attention to the truth that "the contrast between the militant and the industrial is properly between a state in which life is occupied in conflict with other beings, brute and human, and a state in which life is occupied in peaceful labor—energies spent in destruction instead of energies spent in production." Now it is obvious that the latter state is the one in which the growth of the idea of property and the desire to transmit it to offspring would surely be generated, and that if, as is alleged by Mr. Morgan, monogamy owed its origin to the growth of these ideas, then necessarily monogamy and industrialness would surely be connected, and that this is the case, Mr. Spencer thinks unquestioned. He says: "That advance from the primitive predatory type to the highest industrial type has gone along with advance from prevalent polygyny to exclusive monogamy, is unquestionable; and that the decrease of militancy and increase of industrialness have been the essential cause of this change in the type of family, is shown by the fact that this change has occurred where such other supposable causes as culture, religious creed, etc., have not come into play."

It seems to me that, in applying the term monogamy to all forms of the pairing family, from the highest to the lowest, Mr. Spencer is in error. He should, like Mr. Morgan, limit it to that form in which exclusive cohabitation is the law for both man and woman. He should deal with monogamy as an institution. In so dealing with it, we see that it has arisen, as Mr. Spencer has taught us, like all other institutions, by the action of environing agencies on existing social conditions, and that the principal agency in the present case is the growth of the idea of property.﻿R. M.

"THE LAW OF CONTINUITY."

To the Editor of the Popular Science Monthly.

In reply to Mr. Launcelot's letter in the Monthly for February, I would draw attention to the Journal of the Chemical Society, volume viii., page 51, where the late Prof. Graham records certain experiments. He found that sulphuric acid continued to evolve heat when mixed even with the fiftieth equivalent of water that was added to it, so that there seemed to be no distinct limit to chemical affinity. He concludes, "There is reason to believe that chemical affinity passes in its lowest degree into the attraction of aggregation."

As to Mr. Launcelot's paragraph, wherein he states that many metals, other than gold, have been reduced to translucent tenuity, your note makes any answer from me unnecessary.﻿George Iles.